Those who aren't criminals will no longer have to wait days at a detention center that opened for the 1980 Mariel mass migrations.

On Friday, U.S. officials said Cubans who arrive by sea will be processed at Border Patrol stations in the area. They briefly will be checked at a clinic at the detention center in southwest Miami-Dade County before being released. The process would only take a few hours, whereas previously, it could take days.

Cuban migrants with criminal backgrounds still will be detained at Krome, officials said.

Homeland Security Department spokesman Manny Van Pelt said the new procedure reflects a more effective way to use Krome, making more room for criminal migrants awaiting deportation.

Krome is an abandoned Cold War missile base that was reopened in 1980 to process Cuban and Haitian refugees during the Mariel mass migrations.

Since then, most arriving Cuban migrants have been taken there for processing.

Krome's population fluctuates between 400 and more than 500 inmates, all male, on any given day. Its capacity is 580 inmates.

Under the Cuban Adjustment Act, Cubans who reach U.S. soil are not put in deportation proceedings. Instead, the U.S. government helps resettle them and allows them to apply for permanent residence after more than a year in the country.

Some immigrant rights activists criticized the shift in policy, saying it shows preferential treatment for Cuban migrants over others, such as Haitians.

"I'm glad the government is humanely treating Cuban migrants," said Ira Kurzban, a Miami immigration attorney who has fought for increased rights for Haitian migrants. "But it reflects a patently discriminatory policy against Haitians who are incarcerated for months, and sometimes years, and who have claims for political asylum."